This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this project is to develop and apply unique specimen preparation protocols and correlated imaging techniques to examine changes in activity-dependent dendritic spine morphology and synaptic ultrastructure.This work will propel development and application of the tetracysteine/biarsenical labeling system for correlated microscopy and of high resolution imaging, shaping development of methods used for processing, refinement and interpretation of information in reconstructions from electron tomography when specifically applied to the complex problem of deducing the molecular organization of synaptic structures.